A trigonal planar network in hydrogenated epitaxial graphene: a ferromagnetic semiconductor

Hydrogenated epitaxial graphene has distinctive electronic properties compared to the two-sided hydrogenated graphene referred to as graphane. Of particular interest is the experimentally observed room-temperature ferromagnetic semiconducting property, which has remained elusive to theoretical interpretation. Here, we present results of a density functional theory investigation into various hydrogenation patterns. Our results indicate that the stability of a given hydrogenation pattern is strongly influenced by the amount of sp2-hybridized bonding in the structures. A hydrogenation pattern with a trigonal planar network is identified as an intrinsic ferromagnetic semiconductor, which is in very good conformity with experimental observations. Our results provide insight into the structural, electronic, and magnetic properties of hydrogenated epitaxial graphene.